Linoleic acid having conjugated double bonds, which are on the market under the name “CLA” (conjugated linoleic acid), are physiologically active and are used as food additives. A disadvantage is that they are highly hydrophilic and are therefore only incorporated into oil phases or absorbed by fats with difficulty. In addition, they can undergo unwanted reactions with other food constituents, which leads to sensory disadvantages (taste, odor, coloration) and is therefore undesirable. The problem can be avoided if, instead of the free acids, the corresponding triglycerides are used. According to the methods of the prior art, as represented, for example, by German patent DE 19718245 C2 (Cognis), although these conjugated linoleic acid glycerides can be synthesized in principle, it is a disadvantage that they have a comparatively high content of physiologically inactive and unwanted trans, trans-double-bond isomers.
It is therefore an object of the present invention to develop an improved method of preparing conjugated linoleic acid glycerides which is successful with very low equipment requirements and secondly provides products which are distinguished by a very low content of trans, trans-double-bond isomers and a very high content of c9,t11- and t10,c12-isomers.